http://news.windingroad.com/auto-new...sepower-gt500/
The GT500 ROUSHcharger will be offered in three different kits. The simplest upgrade is the addition of a Cold Air Kit with new calibration which nets 45 horsepower.
The next step is including the 2.3L blower in a package which adds 120 horsepower and 88 lb.-ft. torque while keeping a 3-year/36,000 mile warranty. This warranty will not void any offered by the factory. This kit includes the ROUSHcharger, a 78mm non-removable pulley and new calibration..
A non-warranty version will also be offered for off-road use, and this version is anticipated to push the GT500 engine to 700 horsepower, 200 more than the stock engine. Customers will have to purchase a 72mm or 76mm pulley separately, and this version does not include an upgraded calibration. Other modifications may be necessary in order to maximize the horsepower gains.